Synthesis of silicone-vinyl block copolymers (original) (raw)
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Synthesis and Characterization of Block Copolymers Using Polysiloxane Based Macroazoinitiator
Turkish Journal of Chemistry, 2004
Poly(dimethylsiloxane-b-styrene) (PDMS-b-PSt) and poly(dimethylsiloxane-b-methyl methacrylate) (PDMS-b-PMMA) block copolymers containing siloxane segments were studied by the radical polymerizations of vinyl monomers such as styrene (St) and methyl methacrylate (MMA) using polydimethylsiloxane based macroazoinitiator (PDM-MAI) in solution. PDM-MAI was synthesized by reacting hydroxyterminated polydimethylsiloxane (PDMS) and 4,4′-azobis(4-cyanopentanoyl chloride) (ACPC) having a thermodegradable azo-linkage. The polycondensation reaction between PDMS and ACPC (2:1, molar ratio) was carried out at room temperature. The polymerizations of St and MMA initiated by PDM-MAI were investigated using different PDM-MAI concentrations (1, 5, 10, and 15 wt.%) for various reaction times with a methyl ethyl ketone (MEK) / dichloromethane (DCM) solvent mixture (3:1, molar ratio) as the reaction medium at 65 ◦C. The decomposition temperature of MAI azo groups was determined to be 125 ◦C by thermogra...
Journal of Polymer Science Part a Polymer Chemistry, 2007
As a novel synthetic strategy for copolymers of vinyl alcohol, we propose herein copolymerization of alkoxyvinylsilanes with other vinyl monomers, followed by oxidative cleavage of the alkoxysilyl groups attached to the main chain of the resulting copolymers. Radical copolymerization of di(isobutoxy)methylvinylsilane 1 with styrene afforded poly(1-ran-styrene)s with a variety of compositions of both repeating units, although the M n 's (<9000) and yields (<35%) were rather low. The oxidative cleavage of the alkoxysilyl groups in the copolymers with m-chloroperbenzoic acid proceeded efficiently, giving poly(vinyl alcohol-ran-styrene)s, which were soluble in common organic solvents. The structures of the poly(vinyl alcohol-ran-styrene)s were characterized by NMR, GPC, elemental analysis, and matrix-assisted laser desorption time-of-flight mass spectrometry (MALDI-TOF-MS). a Poly(1-ran-St) (0.2-0.5 g) was reacted in 40 mL of DMF; [MCPBA or TMA-O] ¼ 10 3 [repeating unit of 1 in the copolymers]; reaction period ¼ 17-19 h; reaction temperature ¼ 60 8C (run 1, 3-5) or 70 8C (run 2). b M n and M w /M n were obtained by GPC calibration using standard polystyrenes in THF solution.
Preparation of Alkoxysilane Functional Water Soluble Block Copolymers via Raft Polymerization
2017
Alkoxysilane bearing polymers are hybrid compounds that combine the functionality of a reactive group and the inorganic functionality within an organic macromolecule. However, it may be a challenge to prepare copolymers of vinyl silane monomers due to their low reactivity ratios. Present study describes the synthesis of block copolymers of vinyltriethoxy silane (VTES) with various water soluble acrylic polymers (PAA, PMAA, PAAm) using RAFT polymerization technique with different approaches. The polymerization conditions, control on the molecular weights as well as the characterization of obtained block copolymers were discussed in detailed. The FTIR, H-NMR, GPC and DSC analyses verified the presence of VTES segments on block copolymer structure. It was concluded that PMAA-b-PVTES and PAA-b-PVTES diblock copolymers can be synthesized successfully under appropriate reaction conditions.
Journal of The Serbian Chemical Society, 2007
Thermoplastic poly(ester-siloxane)s (TPES) and poly(ester-ether-siloxane)s, (TPEES), based on poly(butylene terephthalate) (PBT) as the hard segment and different siloxane-prepolymers as the soft segments, were prepared. The TPES and TPEES were synthesized by catalyzed two-step transesterification from dimethyl terephthalate, (DMT), 1,4-butanediol, (BD) and a siloxane-prepolymer. Incorporation of dicarboxypropyl-or disilanol-terminated poly(dimethylsiloxane)s (PDMS) into the polar poly(butylene terephthalate) chains resulted in rather inhomogeneous TPES copolymers, which was a consequence of a prononuced phase separation of the polar and non-polar reactants during synthesis. Two concepts were employed to avoid or reduce phase separation: 1) the use of siloxane-containing triblock prepolymers with hydrophilic terminal blocks, such as ethylene oxide (EO), poly(propylene oxide) (PPO) or poly(caprolactone) (PLC) when the terminal blocks serve as a compatibilizer between the extremely non-polar PDMS and the polar DMT and BD, and 2) the use of a high-boiling solvent (1,2,4-trichlorobenzene) during the first phase of the reaction. Homogeneity was significantly improved in the case of copolymers based on PCL-PDMS-PCL.
Block-copolymers with Polyphenyl-α-Naphtylsilane Fragments in Dimethylsiloxane Chain
International Journal of Polymeric Materials and, 2001
The Wurtz-type reductive-coupling reaction of dichlorophenyl-a-naphtylsilanes was carried out both in the presence of metalic sodium in toluene solution and in a mixture of toluene and o-xylene (at I:I ratio) in the presence of sodium and catalytic amount of mercury. Oligomers of a. w-dichlorophenyl-a-naphtylsilanew ith various degrees of polymerization were obtained. By hydrolysis of a,w-dichlorophenyl-a-naphtylsilane the corresponding a,w-dihydroxydiorganosilanes has been obtained. The heterofunctional condensation of a,w-dichloro(dihydroxy)phenyI-a-naphtylsilanes with a,w-dihydroxy( dich1oro)dirnethylsiloxanes in the presence of acceptor pyridine has been carried out and polysilane-siloxane block-copolymers were obtained. Depending on the lengths of the rigid and flexible initial oligomers microdomain structure of block-copolymers were observed. The synthesized block-copolymers were characterized by gel permeation chromatography, differential scanning calorimetry and X-ray methods. Keywork Polysilane; Thermal-oxidative stability; Block-copolymers
Block and graft copolymers with polysiloxane and poly (N‐acyliminoethylene) sequences
Die Angewandte …, 1997
A series of polysiloxane/poly(N-acetyliminoethylene) (PSiOPNAI) block and graft copolymers were synthesized by the initiation of 2-methyl-2-oxazoline (Me-OZO) polymerization with functional polysiloxane prepolymers. The copolymerization products were characterized by IR-and 'H NMR spectroscopy, elemental analysis, DSC and thermogravimetry. The insertion of both hydrophobic and hydrophilic sequences in the macromolecular structure induces a behavior characteristic of amphiphilic compounds. Their solution and solid state behavior evidenced peculiarities which make them able to act as nonionic emulsifiers, surface modifiers, gels, etc.
Synthesis and characterization of poly(ester ether siloxane)s
Polymer International, 2006
A series of novel thermoplastic elastomers based on ABA-type triblock prepolymers, poly[(propylene oxide)–(dimethylsiloxane)–(propylene oxide)] (PPO-PDMS-PPO), as the soft segments, and poly(butylene terephthalate) (PBT), as the hard segments, was synthesized by catalyzed two-step melt transesterification of dimethyl terephthalate (DMT) with 1,4-butanediol (BD) and α,ω-dihydroxy-(PPO-PDMS-PPO) (M̄n = 2930 g mol−1). Several copolymers with a content of hard PBT segments between 40 and 60 mass% and a constant length of the soft PPO-PDMS-PPO segments were prepared. The siloxane-containing triblock prepolymer with hydrophilic terminal PPO blocks was used to improve the compatibility between the polar comonomers, i.e. DMT and BD, and the non-polar PDMS segments. The structure and composition of the copolymers were examined using 1H NMR spectroscopy, while the effectiveness of the incorporation of α,ω-dihydroxy-(PPO-PDMS-PPO) prepolymer into the copolyester chains was controlled by chloroform extraction. The effect of the structure and composition of the copolymers on the transition temperatures (Tm and Tg) and the thermal and thermo-oxidative degradation stability, as well as on the degree of crystallinity, and some rheological properties, were studied. Copyright © 2006 Society of Chemical Industry